Who wants to change down to 3rd gear every time they want to slow down a bit?. No one rides on the freeway in 3rd gear, everyone hums along in top gear and top gear doesn't offer much engine breaking. If you suddenly need to slow down (even if gently) by the time you select 3rd gear it's not going to be a gentle stop anymore.
Who said anything about "changing down to third gear?" When I hit the twisties I typically LEAVE the bike in third gear. You can't damage an engine if you don't exceed redline but you can hit redline and STAY in redline all you want without damaging it. The higher revs give you greater acceleration AND greater deceleration, all of it conveniently controlled by your right wrist.
If you ever get the chance, take either Reg Pridmore's C.L.A.S.S. course or his son Jason's S.T.A.R. school. Even Keith Code covers it in California Superbike School but I first learned the technique under Reg. Although Keith's curriculum is arguably more race-oriented, Reg and Jason's are geared towards street riding.
As for engine wear... my K1200LT just turned over 200,000 miles this past Spring (yes... MILES, not kilometers). It never had any top-end work, and it doesn't burn any more oil than it did when it had only 20,000 miles.